Answer : Southern Blotting (D)
Once we've introduced the gene into a virus culture we can eradicate the first option as it's linked to Bacteria (plasmids are a part of bacteria )
The introduction of gene is itself considered as transformation so option B is eradicated
Transduction is a procedure of genetic recombination in which a virus injects it's genetic material into the host which the whole point of doing this recombination thing.
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